Locomotion assisting device and method

ABSTRACT

An exoskeleton bracing system includes: a trunk support for affixing to the trunk of a disabled person and leg braces for connecting to the legs of the person, each leg brace including limb segment braces. Motorized joints are adapted to provide relative angular movement between the limb segment braces of the leg braces and between the leg braces and the trunk support. One or more ground force sensors are designed to sense ground force exerted on each of the leg braces. The system also includes a controller for receiving sensed signals from said one or more ground force sensors, with an algorithm for identifying a stance from the sensed signals and, based on the identified stance, actuating the motorized joints to perform an action relating to a mode of locomotion selected from a set of predefined actions corresponding to the identified stance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/735,160 filed Jan. 7, 2013, which is a divisionalapplication of U.S. patent application Ser. No. 13/350,852, filed Jan.16, 2012 and issued as U.S. Pat. No. 8,348,875, which is a divisionalapplication of U.S. patent application Ser. No. 12/250,155, filed Oct.13, 2008 and issued as U.S. Pat. No. 8,096,965, all of which are herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to control of a device for assistance withlocomotion. More particularly, the present invention relates to alocomotion assisting device and method.

BACKGROUND OF THE INVENTION

Motorized locomotion assisting exoskeleton devices have been proposedfor assisting people with disabilities to walk or to perform othertasks. In addition to enabling the performance of the tasks, enabling aperson to walk may also impart therapeutic benefits. However, a majordifficulty with such devices has been the lack of ability to controlsuch devices in an effective, safe, and intuitive manner.

U.S. Pat. No. 7,153,242 (Goffer) describes an apparatus for enabling aperson with handicapped lower limbs to walk. The apparatus attaches toparts of the lower portion of the person's body, possibly up to thetorso, and includes motorized means of propelling the parts of the bodyto which it is attached. The apparatus includes sensors for measuringthe angles of the joints, and a sensor for measuring the tilt angles ofthe upper body. The person using the apparatus selects a mode ofoperation, such as a gait. Initiation and maintaining of a gait isindicated by the tilt of the upper body of the person using theapparatus. For example, leaning forward triggers a forward step, andswinging the upper body from an upright position to a forward bendmaintains a walking gait sequence wherein the apparatus performs therequired sequence of movements of the lower limbs, including lifting,extending, bending, and lowering. However, such control by means ofmeasuring the tilt of the upper body may be insufficient. For example,tilting the upper body does not enable the user of the apparatus toindicate with which leg to initiate the gait. Thus, user control islimited. In addition, such an apparatus does not provide controlfeedback for monitoring the phases and progress of the gait, and cannotalert the user to hazardous situations such as a forbidden arrangementof the feet.

Another powered exoskeleton, called a “hybrid assistive limb” or “HAL,”is described by Boyd in “Bionic suit offers wearers super-strength” (NewScientist, issue 2494, 9 Apr. 2005). Two control methods are described.In the first method described, sensors on the skin detect electric nervesignals from the brain to the leg muscles that indicate intention tomove a leg. The device guides movement of the legs in accordance withthe user's intentions. In the second described method, sensors detectwhen the user has started to move. The device then activates itselfautomatically to augment the power of user's muscles. Neither controlmethod may be used by a paraplegic user whose nerves do not transmitsignals from the brain to the legs.

It is an object of the present invention to provide an apparatus andmethod for controlling a locomotion assisting exoskeleton device in anintuitive and natural manner by a paraplegic or other user, and forproviding feedback with regard to performance.

It is a further object of the present invention to provide an apparatusand method for enhancing the safety of a locomotion assistingexoskeleton device.

Other aims and advantages of the present invention will become apparentafter reading the present invention and reviewing the accompanyingdrawings.

SUMMARY OF THE INVENTION

There is thus provided, in accordance with some embodiments of thepresent invention, an exoskeleton bracing system. The system comprises:a trunk support for affixing to the trunk of a disabled person, legbraces for connecting to the legs of the person with each leg braceincluding limb segment braces, motorized joints adapted to providerelative angular movement between the limb segment braces of the legbraces and between the leg braces and the trunk support, one or moreground force sensors designed to sense ground force exerted on each ofthe leg braces, and a controller for receiving sensed signals from theground force sensors. An algorithm identifies a stance from the sensedsignals and, based on the identified stance, actuates the motorizedjoints to perform an action relating to a mode of locomotion selectedfrom a set of predefined actions corresponding to the identified stance

Furthermore, in accordance with some embodiments of the presentinvention, the algorithm includes selecting an action comprisingactuating the motorized jointed limb braces of one leg, when the sensedsignals are indicative of the person leaning on the opposite leg.

Furthermore, in accordance with some embodiments of the presentinvention, the algorithm includes selecting an action comprisingactuating the motorized jointed limb braces of one leg, when the sensedsignals are indicative of the person leaning on the same leg.

Furthermore, in accordance with some embodiments of the presentinvention, the algorithm includes selecting an action comprising endinga currently performed action when the sensed signals are indicative ofsubstantially equally loading both legs.

Furthermore, in accordance with some embodiments of the presentinvention, the algorithm includes selecting an action comprising endinga currently performed action when the sensed signals are indicative ofthe person leaning on a trailing leg.

Furthermore, in accordance with some embodiments of the presentinvention, the system comprises an alerting device, the algorithmincludes selecting an action comprising generating an alert from thealerting device.

Furthermore, in accordance with some embodiments of the presentinvention, the system comprises an alerting device, the action ofgenerating an alert from the alerting device is performed when thesensed signals are indicative of the person falling

Furthermore, in accordance with some embodiments of the presentinvention, the system comprises an alerting device, the action ofgenerating an alert from the alerting device is performed to indicatethat the user is to change the stance.

Furthermore, in accordance with some embodiments of the presentinvention, the algorithm includes selecting an action comprisingcontinuing a currently performed action when the sensed signals areindicative of increasing ground force.

Furthermore, in accordance with some embodiments of the presentinvention, the algorithm includes selecting an action comprisingcontinuing a currently performed action when the sensed signals areindicative of decreasing ground force.

Furthermore, in accordance with some embodiments of the presentinvention, the system comprises a mode selector for selecting the modeof locomotion from a set of predefined locomotion modes.

Furthermore, in accordance with some embodiments of the presentinvention, the mode selector is adapted to communicate with thecontroller via wireless communication.

Furthermore, in accordance with some embodiments of the presentinvention, the mode selector includes a strap for strapping on a wrist.

Furthermore, in accordance with some embodiments of the presentinvention, the mode selector includes controls for selecting modes oflocomotion from a group of locomotion modes consisting of: walking,standing from a sitting position, sitting from a standing position,climbing a stair and descending a stair.

Furthermore, in accordance with some embodiments of the presentinvention, the system comprises a tilt sensor to sense tilt of the trunkof the person with respect to the vertical and to communicate with thecontroller.

Furthermore, in accordance with some embodiments of the presentinvention, the identified stance is determined from the signals receivedfrom said one or more ground force sensors and a signal from the tiltsensor.

Furthermore, in accordance with some embodiments of the presentinvention, the action is selected from a group of actions consisting of:initiating a gait, maintaining a gait, halting a gait, climbing a stair,and descending a stair.

Furthermore, in accordance with some embodiments of the presentinvention, the action comprises enabling continuation of the mode oflocomotion.

Furthermore, in accordance with some embodiments of the presentinvention, there is provided a method of controlling an exoskeletonbracing system that includes a trunk support for affixing to the trunkof a disabled person, leg braces for connecting to the legs of theperson, each leg brace including limb segment braces, motorized jointsadapted to provide relative angular movement between the limb segmentbraces of the leg braces and between the leg braces and the trunksupport, and a controller. The method comprises: providing one or moreground force sensors designed to sense ground force exerted on each ofthe leg braces, receiving sensed signals from the ground force sensors,identifying a stance from the sensed signals, and actuating themotorized joints based on the identified stance to perform an actionrelating to a mode of locomotion selected from a set of predefinedactions that relates to the identified stance.

Furthermore, in accordance with some embodiments of the presentinvention, the step of identifying the stance comprises identifying astance determined by the person.

Furthermore, in accordance with some embodiments of the presentinvention, the identified stance comprises leaning on one leg and theselected action comprises actuating the motorized jointed limb braces ofthe opposite leg.

Furthermore, in accordance with some embodiments of the presentinvention, the identified stance comprises leaning on one leg and theselected action comprises actuating the motorized jointed limb braces ofthe same leg.

Furthermore, in accordance with some embodiments of the presentinvention, the identified stance comprises standing on both legs and theselected action comprises ending a currently performed action.

Furthermore, in accordance with some embodiments of the presentinvention, the identified stance comprises leaning on a trailing leg andthe selected action comprises ending a currently performed action.

Furthermore, in accordance with some embodiments of the presentinvention, the selected action comprises generating an alert.

Furthermore, in accordance with some embodiments of the presentinvention, the system comprises an alerting device, the action ofgenerating an alert from the alerting device is performed when thesensed signals are indicative of the person falling

Furthermore, in accordance with some embodiments of the presentinvention, the system comprises an alerting device, the action ofgenerating an alert from the alerting device is performed to indicatethat the user is to change the stance.

Furthermore, in accordance with some embodiments of the presentinvention, the identified stance comprises falling and the selectedaction comprises generating an alert.

Furthermore, in accordance with some embodiments of the presentinvention, the method comprises detecting increasing ground force toverify the selected action.

Furthermore, in accordance with some embodiments of the presentinvention, the method comprises detecting decreasing ground force toverify the selected action.

Furthermore, in accordance with some embodiments of the presentinvention, the method comprises providing at least one tilt sensor,sensing the tilt of a body part of the person, and using the sensed tiltin the step of actuating the motorized joints.

Furthermore, in accordance with some embodiments of the presentinvention, the action is selected from a group consisting of: initiatinga gait, maintaining a gait, halting a gait, climbing a stair, anddescending a stair.

Furthermore, in accordance with some embodiments of the presentinvention, the mode of locomotion is selected from a group of locomotionmodes consisting of: walking, standing from a sitting position, sittingfrom a standing position, climbing a stair and descending a stair.

Furthermore, in accordance with some embodiments of the presentinvention, the action comprises enabling continuation of the mode oflocomotion.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the present invention, and appreciate itspractical applications, the following Figures are provided andreferenced hereafter. It should be noted that the Figures are given asexamples only and in no way limit the scope of the invention. Likecomponents are denoted by like reference numerals.

FIG. 1A shows a locomotion assisting exoskeleton device in accordancewith embodiments of the present invention.

FIG. 1B shows a control panel unit associated with the locomotionassisting exoskeleton device shown in FIG. 1A.

FIG. 1C is a block diagram of the locomotion assisting exoskeletondevice shown in FIG. 1A and FIG. 1B.

FIG. 2A is a diagram of a control process for initiating a step from astanding position, in accordance with embodiments of the presentinvention.

FIG. 2B is a flow chart of the control process illustrated in FIG. 2A.

FIG. 3 is a diagram of a control process for initiating a step from astanding position using only ground force sensors, in accordance withembodiments of the present invention.

FIG. 4A is a diagram of a control process for maintaining a gait, inaccordance with embodiments of the present invention.

FIG. 4B is a flow chart of the control process illustrated in FIG. 4A.

FIG. 5 is a diagram of a control process for maintaining a gait usingonly ground force sensors, in accordance with embodiments of the presentinvention.

FIG. 6 is a diagram of a control process for standing from a sittingposition, in accordance with embodiments of the present invention.

FIG. 7 is a diagram of a control process for sitting from a standingposition, in accordance with embodiments of the present invention.

FIG. 8A is a diagram of a control process for ascending a stair, inaccordance with embodiments of the present invention.

FIG. 8B is a flow chart of the control process illustrated in FIG. 8A.

FIG. 9A is a diagram of a control process for descending a stair, inaccordance with embodiments of the present invention.

FIG. 9B is a flow chart of the process illustrated in FIG. 9A.

DETAILED DESCRIPTION OF EMBODIMENTS

In accordance with embodiments of the present invention, an apparatusand method are provided to enable effective control and monitoring of amotorized locomotion assisting exoskeleton device by means of groundforce measurement. By “ground force measurement” is meant a localmeasurement of the force that is exerted by an area of a supportingsurface that counters the force exerted on that area of the surface bythe user. The supporting surface may be a floor, or ground, below theuser, or any other horizontal or non-horizontal surface that supportsthe weight of, or otherwise supports or stabilizes the user, or countersa force exerted by the user or the locomotion assisting exoskeletondevice. The ground force may be a force applied directly by thesupporting surface on a component of the locomotion assistingexoskeleton device, or may be transmitted via a body or object that isbetween the supporting surface and the component.

The locomotion assisting exoskeleton device includes braces and supportsthat may be strapped on, or otherwise attached or affixed to, the trunkand sections of limbs and body parts in the lower portion of the body ofa user. The various braces and supports are connected to one another bymeans of joints that enable relative movement between the braces andsupports. The locomotion assisting exoskeleton device may includemotorized actuation assemblies or joints for moving parts of the user'sbody, such as for bending joints in order to propel various limbs of theuser's body. The locomotion assisting exoskeleton device may alsoinclude sensors for measuring relative situation of various componentsof the device, and thus of the body parts to which they are attached.Such sensors may measure, for example, the angle between the bracesections on either side of a joint.

In addition, the locomotion assisting exoskeleton device may include oneor more sensors that sense or measure tilt. For example, such a sensoraffixed to the upper portion of the user's body may measure the tilt ofthat portion of the body.

The user of the locomotion assisting exoskeleton device is provided witha set of controls that communicate with the locomotion assistingexoskeleton device. By means of the controls, the user may select alocomotion mode for the device. Available modes may include walking,climbing a stair, descending a stair, sitting, and standing from asitting position.

In accordance with embodiments of the present invention, the locomotionassisting exoskeleton device includes a foot brace that is positionedunder a foot of the user. The foot brace supports the foot of the user,and applies force to the user's foot that counters the force of theweight of the user on the foot brace. The foot brace is provided withone or more ground force sensors. Ground force sensors are known in theart. For example, a ground force sensor may be based on a forcesensitive resistor, such as a piezoresistive force sensor. A groundforce sensor generates a signal that indicates the force that is appliedto it. The amount of force applied to the ground force sensor depends onthe posture or stance of the user, or on the activity of the user.

When a locomotion mode is selected, the locomotion assisting exoskeletondevice awaits an instruction before initiating the appropriate motionsequence. In accordance with embodiments of the present invention,instructions are provided in accordance with signals generated by theground force sensors of a foot brace. By shifting the weight of theuser's body, perhaps with the aid of crutches, the user may increase ordecrease the force applied to one or more of the ground force sensors.

For example, if a walking gait mode was selected and the user wishes tobegin walking with the right foot, the user slightly leans on the leftfoot (perhaps with concurrent use of crutches). A ground force sensor onthe right foot brace may then generate a signal indicating decreasedforce and a force sensor of the left foot brace may indicate increasedforce. The locomotion assisting exoskeleton device then initiates thewalking gait by lifting and extending the right foot brace. Thelocomotion assisting exoskeleton device continues to monitor the signalsgenerated by the ground force sensors. Thus, the user retains controlover the gait. By leaning or otherwise controlling the force on theground force sensors in an expected manner, the user continues to enablethe gait. If, however, the weight of the user shifts in a mannerinconsistent with the current phase of the gait, the locomotionassisting exoskeleton device may alert the user or halt the gait orconverge to a stance until further instructions are received.

FIG. 1A shows a motorized locomotion assisting exoskeleton device thatis controlled in accordance with embodiments of the present invention.Locomotion assisting exoskeleton device 20 is powered and controlled bycontroller pack 22. Controller pack 22 incorporates a controller in theform of a programmable processor, and a battery or other power supply(shown schematically in FIG. 1C). Controller pack 22 is generally wornon the back of a person using locomotion assisting exoskeleton device20. Alternatively, the various components of controller pack 22 may beattached to or incorporated in various components of exoskeleton device20. For example, components of controller pack 22 may be incorporatedinto braces 24.

Controller pack 22 may communicate with a tilt sensor 23 that is fixedto a location on the upper portion of the user's body. For example, tiltsensor 23 may be worn on a shoulder strap that holds controller pack 22to the user's torso, and thus senses the degree of tilt of the torso.The tilt sensors may include accelerometers, gyroscopes, or any othersensors capable of being incorporated in a locomotion assistingexoskeleton device and designed to sense tilt. The tilt sensor generatesa signal that indicates whether the user's upper portion of the body isleaning or is upright with respect to the vertical

Braces 23 are affixed by means of straps 25 to segments of the user'slower limbs and to the pelvis, torso, or other parts of the user's body.Braces 23 incorporate motorized actuation assemblies 24. Each actuationassembly 24 includes a motorized actuator (not shown) that, in responseto commands transmitted by controller pack 22, causes a joint thatconnects between individual braces 23 to bend or extend. Bending orextending a joint may propel or move a limb to which an adjoining braceis attached. When the lower limbs of the user are affixed to braces 23,each of the user's feet is placed on a foot brace 26. Foot brace 26 maybe movable by means of a separate motorized actuation assembly (notshown) to lift, guide, and lower a foot of the user. Alternatively, footbrace 26 may include a coil, spring, or other elastic anti-dropmechanism associated with ankle joint 27. The anti-drop mechanismassociated with ankle joint 27 holds foot brace 26 substantiallyhorizontal when foot brace 26 is raised above, and is not supported by,a supporting surface.

FIG. 1B shows a control panel unit associated with the motorizedlocomotion assisting exoskeleton device shown in FIG. 1A. Control panelunit 30 communicates with controller pack 22 via a wireless or othercommunications channel. Typically, control panel unit 30 is strapped tothe user's wrist by means of straps 34. Control panel unit 30 includesone or more touch-sensitive buttons or keys 32. The touch-sensitivebuttons 32 may serve as a mode selector to select a mode of locomotion,to verify a command, or to communicate other instructions to controllerpack 22.

One or more ground force sensors 28 are mounted on each foot brace 26.Each of ground force sensors 28 is capable of generating a signal thatindicates the force applied to that sensor. Signals generated by groundforce sensors 28 are transmitted to controller pack 22. Controller pack22 receives signals transmitted by control panel unit 30 and by groundforce sensors 28. On the basis of the received signals and in accordancewith programmed instructions, controller pack 22 transmits instructionsto actuation assemblies 24. The instructions transmitted to actuationassemblies 24 may cause one or more of braces 23 to move, propelling anylimbs attached to the units.

By activating buttons 32 and by adjusting the force on ground forcesensors 28, a person may control locomotion assisting exoskeleton device20 to assist in performing a desired task. Examples of controlling alocomotion assisting exoskeleton device in accordance with embodimentsof the present invention are described below.

FIG. 1C is a block diagram of the locomotion assisting exoskeletondevice shown in FIG. 1A and FIG. 1B. Power supply 15 is located incontroller pack 22. Main supply 16 provides power to main processor 12,actuation assemblies 24, and motors 38. Main supply 16 may include arechargeable battery that may be charged by means of charger unit 18that may be connected to main supply 16 through protection circuit 19.When necessary, an appropriate alternative external power source, suchas an auxiliary battery, may be connected to auxiliary connection 17.

Main processor 12 may receive signals from tilt sensor 23 and groundforce sensors 28. Main processor 12 may communicate with control unit 30over a wireless connection through wireless communications board 14.Main processor 12 communicates with actuation assemblies 24 viacommunications channels, such as controller-area network (CAN) bus 37.Each actuation assembly 24 includes a control board 36. Each controlboard 36 controls a motor 38 that determines the motion of actuationassembly 24, and thus of a brace or joint to which actuation assembly 24may be attached.

In general, a user of locomotion assisting exoskeleton device 20 selectsa mode of operation. Modes of operation may include selection of a taskto be carried out. Examples of such tasks may include walking with aparticular gait, sitting, standing from a sitting position, climbingstairs, and descending stairs.

The locomotion assisting exoskeleton device may include one or morealerting devices for alerting the user of situations demanding theuser's attention. Such alerting devices may generate audible, visible,or tactile alert signals. The alerting devices may be incorporated intoone or more components of the locomotion assisting exoskeleton device.Situations requiring user attention may include contradictory orunexpected movements or foot loading, falling, and points during theexecution of a procedure where user verification is required for safetypurposes.

Depending on the details of the control algorithm for the motorizedlocomotion assisting exoskeleton device, the ground force sensor valuesused in controlling the locomotion assisting exoskeleton device mayrepresent a signal generated by a single sensor, or may be arepresentative value of the signals based on processing the outputsgenerated by part or all of an array of sensors associated with a singlefoot brace. Alternatively, the value used may represent a pattern or mapof forces applied to the sensors of one or both foot braces.

For the sake of simplicity in the discussion below, the values of forcesmeasured by the ground force sensors, or foot loadings, may beclassified into one of four loading categories. The ranges of sensorsignals to be included within each loading category may vary from userto user, or from one mode of operation to another. The loadingcategories may also be defined relative to one another. The categoryrepresenting the range of the smallest forces may be labeled “foot off”(FO), and is associated with a foot brace that is not touching theground. The category representing the next larger range of forces may belabeled “foot touching” (FT), associated with a foot brace that istouching the ground, but with minimal loading. The category representingthe next larger range of forces labeled “foot lightly loaded” (FLL), mayrepresent light loading on a foot brace, associated with a situationwhere the user is standing on both feet, and load of the weight of thebody is shared with the other foot brace. Finally, a categoryrepresenting the range of greatest forces may be labeled “foot heavilyloaded” (FHL). FHL is associated with a user leaning on one foot brace,with that foot brace supporting most of the weight of the user's body.

In addition to the signal output of ground force sensors, control of thelocomotion assisting exoskeleton device may utilize a measurement of thetilt of the upper part of the user's body. The tilt measurement may beused to check whether the tilt of the user's body is consistent with thecurrent phase of an activity. In addition, depending on the controlalgorithm of the locomotion assisting exoskeleton device, the user mayuse body tilt, in addition to applying force to the ground forcesensors, to control the locomotion assisting exoskeleton device.

Loading on a particular foot, the right or the left foot is indicated inthe discussion below by preceding the abbreviation for a loadingcategory with the letter R or L, respectively. For example, the rightfoot lightly loaded may be designated RFLL. The left foot touching maybe designated LFT.

Various combinations of loading on the right and left legs may indicatevarious stances. A stance is to be understood as including any postureof the body, such as, for example, standing, sitting, or a phase of awalking gait, including an unstable or falling posture, and not only astable standing posture. For example, a loading combination RFLL andLFLL may indicate that the user is standing straight or otherwiseplacing approximately equal loading on both legs. A combination of RFHLwith lighter loading on the left leg, LFLL, LFT, or LFO, may be indicatethat the user is leaning on the right leg. Conversely, a combination ofLFHL with RFLL, RFT, or RFO may indicate leaning on the left leg.Leaning on a leg is understood to include standing on one leg with theother leg being held above the ground. Any combination of FLL, FT, or FOloading on one leg, combined with FT or FO loading on the other leg, mayindicate falling. Falling may also be indicated by a tilt sensor. Duringfalling, the tilt sensor may indicate that the upper body is tilted atan angle indicative of falling, or may indicate acceleration indicativeof falling.

In the diagrams discussed below, the left leg is designated LG, theright leg is designated RG, and ground force sensors are designated GF.In the examples of the control methods described below, the user maycoordinate the action of the locomotion assisting exoskeleton devicewith the use of crutches. However, the role of the crutches is notindicated in the Figures.

FIG. 2A is a diagram of the control process for initiating a step from astanding position, in accordance with embodiments of the presentinvention. FIG. 2B is a flow chart of a control method for the processillustrated in FIG. 2A. By means of the controls on the control panelunit of the exoskeleton skeleton device, the user indicates theintention to initiate a walking gait (step 140). The control system ofthe locomotion assisting exoskeleton device then checks whether tiltsensors indicate that the user is leaning forward (step 142). If not(step 57), the system checks whether a predetermined time has elapsedsince step 140 (step 144). If the time has elapsed, the process ofinitiating a walking gait times out and is halted (step 58). If not, thesystem continues to wait for an appropriate signal from the tilt sensors(return to step 142).

The user initiates the walking gait by leaning forward (step 41). Theuser may be initially standing with weight distributed approximatelyequally between both legs (as in step 40, RFLL and LFLL loading). If nochange in loading is detected by the ground force sensors within apredetermined period of time (step 150), the process of initiating awalking gait times out and is halted (step 58). The user may lean on theright leg (RFHL loading, step 42) to instruct the locomotion assistingexoskeleton device to begin a walking gait, stepping with the left legfirst. Leaning on the right leg is a relatively intuitive way ofindicating that the user wishes to start walking by stepping with theleft leg. When the control system detects leaning on the right leg, thesystem executes an algorithm (step 44) causing the locomotion assistingexoskeleton device to extend the left leg. The user is then standingwith left leg extended (step 46). The system records that a walking stepwas made with the left leg (step 146) and the gait maintenance process(described below) begins (step 48). If the user prefers to start thegait with the right leg, the user leans on the left leg (LFHL loading,step 50). This initiates a walking step with the right leg (step 52 andstep 54) that is recorded by the system (step 148). During the processof initiating a gait, the locomotion assisting exoskeleton devicecontinues to monitor the ground force sensors. Should the ground forcesensors indicate falling (step 56, FLL, FT, or FO loading on one legcombined with a FT or FO loading on the other), or a tilt sensorindicate falling, the walking gait initiation procedure is halted (step58).

Alternatively, initiating a gait by the locomotion assisting exoskeletondevice may be controlled by means of activating the ground force sensorsalone, without waiting for a signal from a tilt sensor. FIG. 3 is adiagram of control for initiating a step from a standing position usingonly ground force sensors, in accordance with embodiments of the presentinvention. Leaning on either leg initiates the gait initiation process.If the ground force sensors do not indicate that the user has leaned oneither leg within a predetermined period of time, the gait initiationprocess times out and is halted.

FIG. 4A is a diagram of the control process for maintaining a gait, inaccordance with embodiments of the present invention. FIG. 4B is a flowchart of a control method for the process illustrated in FIG. 4A. Beforeinitiating another walking step of the gait, the system checks if thetilt sensors indicate that the user is leaning forward. If not (step57), and a predetermined time period has elapsed (step 144), the gaitmaintenance process times out.

When the process times out, an algorithm is executed (step 70) to bringboth legs to a standing position (step 40) and the process is halted(step 58).

The user indicates the intention to continue the walking gate bycontinuing to lean forward (step 47). If the previous step of the gaitwas executed with the left leg, the user may be standing in the positionof step 46, with left leg extended forward. The user leans on theextended left leg (step 60) to instruct the locomotion assistingexoskeleton device to continue the walking gait by extending the rightleg (step 62). The system records that the last step of the gait wasexecuted with the right leg. The user is now in the position of step 54,with right leg extended. On the other hand, while standing in theposition of step 46, the user may lean on the trailing right leg (step68) or on both legs with about equal force. Continuing to lean on thetrailing right leg or on both legs for a predetermined time interval(step 150) instructs the locomotion assisting exoskeleton device to haltthe walking gait. The system executes an algorithm (step 70) to bringthe user's legs together to a standing stance, to the position of step40. The walking process is then halted (step 58).

If the previous step of the gait was executed with the right leg so thatthe user stands with right leg extended (step 54), the user may lean onthe extended right leg to instruct the locomotion assisting exoskeletondevice to continue a forward gait by extending the left leg (step 64).The locomotion assisting exoskeleton device then executes a step of thegait with the left leg forward (step 66) so that the user is standingwith the left leg extended (step 46). The system records that a step wasexecuted with the left leg (step 146). On the other hand, while stillstanding in the position of step 54, leaning on the trailing left leg(step 74) or about equally on both legs (step 40) for a predeterminedtime interval (step 150) instructs the locomotion assisting exoskeletondevice to bring the user to a standing position (step 70 and step 40)and to stop the gait maintenance process (step 58).

After taking a step of the gait, with the having one leg extended (step46 or step 54), the system again checks for tilt (step 142) and repeatsthe step process. If during execution of a step of the gait, the groundforce sensors or a tilt sensor indicate that the user is falling (step56), the gait maintenance process is halted (step 58). Alternatively,the process of maintaining a walking gait of the locomotion assistingexoskeleton device may be controlled by means of activating ground forcesensors alone, without waiting for a signal from a tilt sensor. FIG. 5is a diagram of the control process for maintaining a gait using onlyground force sensors, in accordance with embodiments of the presentinvention. Leaning on the extended leg signals continuation of the gaitmaintenance process. If the ground force sensors do not indicate thatthe user has leaned on the extended leg within a predetermined period oftime, the gait maintenance process times out, the legs are broughttogether to a standing-straight position, and the process is halted.

FIG. 6 is a diagram of the control process for standing from a sittingposition, in accordance with embodiments of the present invention. Theuser, in a sitting position, uses the control panel unit of thelocomotion assisting exoskeleton device to signal the locomotionassisting exoskeleton device that the user wishes to stand. In order toinstruct the locomotion assisting exoskeleton device to initiate thestanding procedure, the user places both feet on the ground (step 80, FTloading on both legs). The locomotion assisting exoskeleton deviceinitiates a standing procedure algorithm (step 82). The locomotionassisting exoskeleton device begins straightening the user's legs (step84 and step 86), bringing the user to a standing position (step 88).While executing the standing procedure, the locomotion assistingexoskeleton device monitors the output signals of the ground forcesensors. If the standing procedure proceeds as expected, the groundforce sensors measure increasing force during steps 84 and 86 until thefull standing position of step 88 is attained (RFLL and LFLL loading).Alternatively or additionally, progress of the standing procedure may bemonitored by means of sensors that sense the angles of the variousjoints, and that are incorporated in the actuation assemblies of thelocomotion assisting exoskeleton device. Deviation from the expectedincrease in force, or change in joint angle, for a predeterminedinterval of time may be interpreted as indicating a problem with thestanding procedure. In such a case, the locomotion assisting exoskeletondevice may alert the user, and may halt or suspend the standingprocedure until further instructions are received or may return the userto a sitting position 80.

Another safety means may involve a tilt sensor that senses the tiltangle of a part of the upper body of the user. If the tilt sensorindicates that the user is falling, the locomotion assisting exoskeletondevice may act to attempt to prevent or mitigate the effects of thefall. For example, the locomotion assisting exoskeleton device may causethe user to sit back.

FIG. 7 is a diagram of the control process for sitting from a standingposition, in accordance with embodiments of the present invention. Whilestanding in front of a surface on which the user wishes to sit, the useruses the control panel unit to instruct the locomotion assistingexoskeleton device to execute a sitting procedure. The user standsstraight, with approximately equal force (FLL loading) on both legs(step 90). This signals the locomotion assisting exoskeleton device toinitiate a sitting procedure algorithm (step 92). The locomotionassisting exoskeleton device bends the user's legs (step 94 and step96), bringing the user to a sitting position (step 98). While executingthe sitting procedure, the locomotion assisting exoskeleton devicecontinues to monitor the ground force sensors. It is expected that theground force sensors will indicate decreasing ground force until a fullsitting position is attained (RFT and LFT loading). Alternatively oradditionally, progress of the sitting procedure may be monitored bymeans of sensors that sense the angles of the various joints, and thatare incorporated in the actuation assemblies of the locomotion assistingexoskeleton device. A deviation from the expected decrease in force, orchange in joint angle, for a predetermined interval of time may beinterpreted as indicating a problem with the sitting procedure. Theprocedure may then be stopped or paused until further instructions arereceived. If a tilt sensor indicates that the user may be falling duringthe sitting procedure, the sitting procedure may be stopped, and actionmay be taken to prevent, or mitigate the effects of, the fall.

FIG. 8A is a diagram of the control process for ascending a stair, inaccordance with embodiments of the present invention. FIG. 8B is a flowchart of a control method for the process illustrated in FIG. 8A. Toascend a stairway of several stairs, the control process is repeated foreach consecutive stair. To initiate the process of ascending a stair, auser standing below a stair to be ascended uses the control panel unitto instruct the locomotion assisting exoskeleton device to execute astair ascending procedure (step 160). The system then checks if theground force sensors indicate that the user is leaning on a single leg(step 162). The user leans on one leg to instruct the locomotionassisting exoskeleton device to initiate the procedure by placing theopposite leg on top of the stair. If the user does not lean on a singleleg but continues to stand on both legs, the locomotion assistingexoskeleton device alerts the user (step 163).

In this example, the user leans on the left leg (step 100). Forsimplicity, we limit the discussion here to an example in which the userleans on the left leg in order to begin the ascent with the right leg.However, the description of the procedure remains valid if right andleft legs are interchanged throughout. In response to leaning on theleft leg, the locomotion assisting exoskeleton device executes analgorithm for lifting the right leg and extending it forward above thestair (step 102). With the right leg positioned above the stair, theground force sensors are expected to indicate that the user is standingon the left leg (step 104). The locomotion assisting exoskeleton devicethen executes an algorithm to lower the right leg (step 106), checkingthe ground force sensors on the right foot brace (step 170) until thesensors indicate that the right foot has touched the top of the stair(RFT loading) while leaning on the left leg (step 108). At this pointthe output signals from the ground force sensors are monitored to checkwhether the right foot is fully resting on the stair (step 172). Forexample, input signals from sensors in both the toe and heel of theright foot brace may be checked to verify that all sensors indicate atleast minimal contact (FT loading). If the sensor signals indicate thatall or part of the right foot is not resting on top of the stair withina predetermined time interval, the algorithm assumes that the procedurehas failed. In the event of such failure, the locomotion assistingexoskeleton device may return the right foot to its original position asat the beginning of the procedure (step 173), i.e. the position of step100. The procedure is then halted until further instructions arereceived (step 58).

If the sensors indicate that the procedure has continued as expected,and that the right foot is fully resting on top of the stair, thelocomotion assisting exoskeleton device may alert the user to this bygenerating an audible or other signal. For safety reasons, thelocomotion assisting exoskeleton device may then await acknowledgment orverification from the user before proceeding to the next step inascending the stair (step 174). The user may indicate verification bymeans of a control button, or by any other appropriate control orsignaling means known in the art. Once verification is received from theuser, system checks whether the user is leaning on the right leg (step176). In addition, the system may verify that a tilt sensor indicatesthat the user's torso is leaning forward. If the user leans on the rightleg (step 110), the system executes an algorithm to lift the left legand the user's body to the top of the stair (step 112). Failure to leanon the right leg, or to lean forward, within a predetermined timeinterval may indicate the user's stance is inconsistent with safelyproceeding with the ascend stair procedure. Therefore, failure to leanon the right leg, or to lean forward, may cause the locomotion assistingexoskeleton device to alert the user and to stop the procedure untilfurther instructions are received (step 178). When step 112 is complete,the left leg is brought into line with the right leg on top of thestair. The user is then standing on top of the ascended stair (step114). At this point, the user may use the control panel unit to instructthe locomotion assisting exoskeleton device to execute a procedure tobegin a walking gait, to ascend another stair, or any other appropriateaction. Throughout the stair ascending procedure, the stability andsafety of the user may be achieved by concurrent use of crutches or ahand railing. During execution of the stair ascending procedure, theground force sensors or a tilt sensor may indicate that the user isfalling. The locomotion assisting exoskeleton device may then takeaction to prevent, or mitigate the effects of, a fall. For example, thelocomotion assisting exoskeleton device may attempt to restore balanceto prevent a fall, may cause the user to collapse in such a manner as toreduce the impact of a fall.

FIG. 9A is a diagram of the control process for descending a stair, inaccordance with embodiments of the present invention. FIG. 9B is a flowchart of a control method for the process illustrated in FIG. 9A. Todescend a stairway of several stairs, the control process is repeatedfor each consecutive stair. To initiate the process of descending astair, a user standing on an upper level above a stair to be descendeduses the control panel unit to instruct the control system of thelocomotion assisting exoskeleton device to execute a stair descendingprocedure (step 182). The user leans on one leg to instruct thelocomotion assisting exoskeleton device to initiate stair descentprocedure with the opposite leg. If the user does not lean on a singleleg (step 184) but continues to stand on both legs, the locomotionassisting exoskeleton device alerts the user (step 186).

In this example, the user leans on the left leg (step 120). Forsimplicity, we limit the discussion here to an example in which the userleans on the left leg in order to begin the descent with the right leg.However, the description remains valid if right and left legs areinterchanged throughout. In response to leaning on the left leg, thesystem executes an algorithm for extending the right leg forward abovethe stair (step 122). While extending the right leg, the systemcontinues to check if the right foot is no longer touching the upperlevel (RFO loading, step 190). When the right leg is extended above thestair, the ground force sensors are expected to indicate RFO loading onthe right foot, and that the user is standing on the left leg (step124). At this point, for reasons of safety, the system may wait for anacknowledgement signal indicating verification by the user (step 192).Verification from the user may be understood to indicate that crutchesare properly positioned, or other precautions have been taken, to assureproper support of the user's body during the next steps of theprocedure. If verification is received, the locomotion assistingexoskeleton device then executes an algorithm for bending the left knee(step 127), lowering the right leg. During execution of the algorithm ofstep 127, the ground force sensors may indicate a state equivalent tofalling, with a combination of RFO and LFLL or LFT loading (step 126).However, in reality, the weight of the user is being supported bycrutches or other means. During this phase of descending a stair, a truestate of falling may be indicated only by a tilt sensor or similarsensor, and not by the ground sensors. While bending the left knee, thesystem checks the ground force sensors for RFT loading (step 194) thatmay indicate that the right foot has made contact with the top of thestair. When RFT loading is indicated, the right foot is expected to reston the top of the stair the algorithm of step 127 ceases to execute. Theground force sensors are checked to verify that the user is leaning onthe right leg (step 196). If not the user is alerted (step 198). Whenthe user leans on the right leg (step 128), the system begins executionof an algorithm to remove the left leg from the upper level (step 130).The locomotion assisting exoskeleton device lifts the left leg at thehip and bends the left knee to remove the left foot from the upperlevel. This action continues as long as the ground force sensorsindicate LFT loading (step 131). When the ground force sensors indicateLFO, the left foot is expected to be positioned above the stair, withthe user leaning on the right leg (step 132). The system then executesan algorithm that causes the locomotion assisting exoskeleton device tolower the left foot until the left foot touches the top of the stair(step 134). When step 134 is complete, the user is standing with bothlegs on top of the stair (step 136). At this point, the user may use thecontrol panel unit to instruct the locomotion assisting exoskeletondevice to execute a procedure to begin a walking gait, to descendanother stair, or any other appropriate action. Throughout the stairdescending procedure, the stability and safety of the user may beachieved by concurrent use of crutches or a hand railing.

It should be understood that in the above descriptions of examples ofcontrol processes, steps of the processes may have been omitted for thesake of clarity and simplicity. Also, variations of the processes andprocedures described above may be apparent to one skilled in the art,and are to be considered as falling within the scope of the presentinvention.

Examples of such variations are: additional or different points during aprocedure where user verification may be required, different means ofindicating user verification or monitoring a procedure, additionaltimeout intervals that were not indicated in the above discussion, useof tilt sensor output in procedures where such use was not described inthe above discussion, use of angle sensor output, changing the order ofindividual steps of the procedure, and other variations.

Thus, as described above, a system for the convenient, safe, andintuitive control of a locomotion assisting exoskeleton device isprovided.

It should be clear that the description of the embodiments and attachedFigures set forth in this specification serves only for a betterunderstanding of the invention, without limiting its scope.

It should also be clear that a person skilled in the art, after readingthe present specification could make adjustments or amendments to theattached Figures and above described embodiments that would still becovered by the present invention.

1. A method of controlling an exoskeleton bracing system to ascend astair, the exoskeleton bracing system including a trunk support, legbraces, each leg brace including limb segment braces, motorized jointsadapted to provide relative angular movement between the limb segmentbraces of the leg braces and between the leg braces and the trunksupport, one or more ground force sensors for sensing a ground forceexerted on each of the leg braces, and a controller, the methodcomprising: when a sensor signal from said one or more ground forcesensors indicates leaning on one leg, actuating the motorized joints tolift a leg brace of an opposite leg so as to extend the leg forward, andto lower the opposite leg until the sensor signal indicates that theopposite leg is in contact with a top of the stair; actuating themotorized joints to straighten the opposite leg when an acknowledgementis received and when the sensor signal indicates contact of the oppositeleg with the top of the stair and when the sensor signal furtherindicates leaning on the opposite leg, and to move said one leg forwarduntil adjacent to the opposite leg.
 2. The method of claim 1, whereinthe verification is generated by operation of a control by a user of theexoskeleton bracing system.
 3. The method of claim 2, wherein thecontrol is a control button.
 4. The method of claim 1, comprisinggenerating a signal to alert a user of the exoskeleton bracing systemwhen awaiting the verification.
 5. The method of claim 1, comprisingreturning the opposite leg brace to its original position if the sensorsignal does not indicate contact of the opposite leg with the top of thestair within a predetermined time interval.
 6. The method of claim 1,comprising alerting a user of the exoskeleton bracing system if thesensor signal does not indicate said leaning on the opposite leg withina predetermined time interval.
 7. The method of claim 1, wherein theexoskeleton bracing system comprises a tilt sensor.
 8. The method ofclaim 7, wherein the actuating of the motorized joints to straighten theopposite leg is performed when the tilt sensor indicates that a user ofthe exoskeleton bracing system is leaning forward.
 9. The method ofclaim 8, comprising alerting a user of the exoskeleton bracing system ifthe tilt sensor does not indicate leaning forward within a predeterminedtime interval.